package com.lihui.linkedlist;

import java.util.List;

/**
 * 功能描述
 *
 * @author wileda
 * @date 2022/10/13  22:41
 */
public class DoubleLinkedList {
    private static  class ListNode{
        int val;
        ListNode next;
        ListNode prev;

        public ListNode(int val) {
            this.val = val;
        }
    }
    public ListNode head;
    public ListNode tail;

    public void addFirst(int data){
        ListNode node = new ListNode(data);
        if(head == null){
            head = node;
            tail = node;
        }else {
            node.next = head;
            head.prev = node;
            head = node;
        }
    }

    public void addLast(int data){
        ListNode node = new ListNode(data);
        if (head == null){
            head = node;
        }else {
            tail.next = node;
            node.prev = tail;
        }
        tail = node;
    }
    public void addIndex(int index, int data) {
        checkRangeForAdd(index);
        if(index == 0){
            addFirst(data);
            return;
        }
        if (index == size()){
            addLast(data);
            return;
        }
        ListNode tempNode = findNodeByIndex(index);
        ListNode node = new ListNode(data);
        node.next = tempNode;
        node.prev = tempNode.prev;
        node.prev.next = node;
        node.next.prev = node;
    }

    private ListNode findNodeByIndex(int index) {
        ListNode current = head;
        while(index > 0){
            current = current.next;
            index--;
        }
        return current;
    }

    private void checkRangeForAdd(int index) {
        if (index < 0 || index > size()){
            throw new IndexOutOfBoundsException("下标不合法，index = " + index);
        }
    }

    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key){
        ListNode current = head;
        while(current != null){
            if (current.val == key){
                return true;
            }
            current = current.next;
        }
        return false;
    }
    //删除第一次出现关键字为key的节点
    public void remove(int key){
        if (head == null){
            return;
        }
        ListNode current = head;
        while (current != null){
            if(current.val == key){
                if(current == head){
                    head = head.next;
                    if(head == null){
                        tail = null;
                    }else {
                        head.prev.next = null;
                        head.prev = null;
                    }
                }else if (current == tail){
                    tail = tail.prev;
                    tail.next = null;
                }else {
                    current.next.prev = current.prev;
                    current.prev.next = current.next;
                }
                return;
            }
            current = current.next;
        }
    }
    //删除所有值为key的节点
    public void removeAllKey(int key){
        if (head == null) {
            return;
        }
        ListNode current = head;
        while (current != null) {
            // 头节点
            if (current.val == key) {
                if (current == head) {
                    head = head.next;
                    // 删除头节点
                    if (head == null) {
                        // 链表已经为空
                        tail = null;
                    } else {
                        // 只剩一个节点
                        head.prev = null;
                    }
                } else if (current == tail) {
                    // 处理尾节点
                    tail = tail.prev;
                    tail.next = null;

                } else {
                    current.next.prev = current.prev;
                    current.prev.next = current.next;
                }
            }
            // 继续遍历
            current = current.next;
        }
    }
    public int size() {
        int count = 0;
        ListNode current = head;
        while(current != null){
            count++;
            current = current.next;
        }
        return count;
    }

    public void display() {
        StringBuilder sb = new StringBuilder();
        sb.append("[");
        ListNode current = head;
        while(current != null){
            sb.append(current.val);
            if (current.next != null){
                sb.append(",");
            }
            current = current.next;
        }
        sb.append("]");
        System.out.println(sb.toString());
    }
}
